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Patented Nov. 17, 1953 UNITED STATES PREPARATION OF LEUCO-INDANTHRONE SULFURIC ESTERS William B. Hardy, Bound Brook, and Robert B; Fortenbaugh, Gladstone, N. J., assignors to American Cyanamid Company, New York, N. Y.,

a corporation of Maine No Drawing. Application February 15, 1952, 'Serial No. 271,868

This invention relates to an improved process of preparing leuco indanthrone tetrasulfuric esters by the oxidative condensation of leuco betaaminoanthraquinone disulfuric esters.

actions.

drawbacks.

sents serious problems.

in spite of its high cost.

of oxidation.

compounds.

metals.

diners.

any theoretical explanation.

cal.

16 Claims. (Cl. 260-265) spent oxidizing agent readily and substantially quantitatively by filtration and; if desired, it can be regenerated and reused. The product is obtained in the filtrate from which it can be isolated in good yields and satisfactory purity by beta-aminoanthraquinone,

3 bromo-2- and These include barium The invention, of course,

In the past, the production of leuco indan- 5 throne tetrasulfuric esters has been attempted conventional means. with various oxidizing agents, such as ferricy- The present invention is applicable generally to anides, hypochlorites and lead dioxide, which are leuco sulfuric esters of beta-aminoanthraquiusable under alkaline conditions. These pronones, the only requirement of course being that cedures have been subject to undesirable side rethere be a free alpha p t n a ja ent t the These have been particularly serious amino group. Typical esters which may be used with the alkali metal ferricyanides and hypochloare the following: rites; and as a result the only process which has B-chloro -2- aminoanthraquinone, had any practical significance is one using lead aminoanthraquinone, 2-aminoanthraquinone-3- dioxide under alkaline conditions as the oxidizcarboxylic acid, 2-amino-3-methyl anthraquiing agent. While this process has been sufiiciently none, 2-amino-3-methoxyanthraquinone; effective to be used for actual practical produccompounds containing condensed rings, such as tion of the esters, it suffers from a number of 1,2-benz-3-aminoanthraq are also Suitable- Lead is expensive and its high mo- Esters may be used in the form of the amino comlecular weight makes it a very wasteful oxidizp nds r. f ir eir N- y riv v ing agent. The cost of the lead is so high that such as acetylamino and sulfamido compounds no process using it as an oxidizing agent can be may be empl y and throughout the specification carried out without recovery of lead, which preand claims the term a beta-aminoanthraqui- The drawbacks to the none includes the beta-acyl amino anthraquilead dioxide process are sufiiciently serious so nones as well as those having a free amino group. that it has even been proposed to use silver oxide While the i p oved r u t f t e p nt invention are obtainable with any compounds of According to the present invention, we have the metals of group VIII in their higher state of found that if simple compounds, not complexes, oxidation, certain specific compounds of this class of the metals of group VIII of the periodic sysare readily obtainable and are, therefore, prefertern, having atomic numbers 26, 2'7 and 28, i. e., able for economic reasons. iron, cobalt and nickel, are used as oxidizing and strontium perferrites, alkali and alkaline agents, the reaction proceeds smoothly and no earth metal ferrates, such as ferrates of sodiniculty is encountered. However, in order to dium, potassium, calcium and barium; cobaltic be oxidizing agents for practical purposes, in these hydroxides, cobaltic dioxide and oxides of tricompounds the metal must be in a higher state and tetravalent nickel.

In the case of iron, the valence is not limited to the use of these preferred oximust be l or 6, trivalent ferric iron will not opdizing agents. erate satisfactorily. Cobalt in the tri and tetra- The invention will be described in greater devalent state and nickel in the tri and tetravalent tail in conjunction with the following specific state may also be used in the form of their simple examples, the parts being by weight unless other- Not only do the oxidizers of the Wise indicated. present invention operate smoothly and efficiently, but their low molecular weight improves output. Example 1 It is not known why the improved results are so specific to the higher oxidation state of the three A mlxtur? of parts of the potassium salt of Ordinarily, Complex trivalent iron Z-acetylammo chloro-anthrahydroquinonepounds such as ferricyanides are powerfulpoxi- F f acld ester 4 P sodium Yet in the present process, they do not dioxide, and 35 parts of water is stlrred at 85 till give useful'results, whereas tetravalent and hex- 60 1137913157518 Ofthe acetyl group is complete as indi' malem iron cgmpounds can be used Very efiec catedby the failure of any precipitate to form tively. We do not know Why th 'higher t t w en a drop of the reaction solution is diluted oi oxidation give the improved results and it is with 2 9 Water and treated with a few crys' i t n j d to limit the present invention to tals of sodium nitrite followed by dilute hydro- ChlOIiC acid. it is an advantage of the present invention To the hydrolyzed solution containing the dithat the reaction conditions are in no sense criti- Sulfuric ester of 2amino'3-ch101'anthmhydr0 The reactmn prgceeds readily in aqueous quinone, is added 5.5 parts of cobaltic hydroxide medium at moderate temperatures, preferably Prepared y a g -5 p ts of cobaltous acetate slightly above room temperature. When the reto a solution of 10 parts of potassium hydroxide in action is complete, it is possible to recover the parts by volume of 15% sodium hypochlorite solution, filtering and washing the resulting black precipitate.

The reaction mixture is held at 85 until oxidation is complete, filtered, concentrated to 80 parts by volume, and salted with 20 parts of potassium chloride. After thorough stirring and cooling. the product is filtered. A good yield of the tetrasulfuric acid ester of the dichloro leuco indanthrone is obtained.

Example 2 Barium ferrate is prepared by adding a solution of 13.5 parts of ferric chloride in 20 parts of water to a solution of 20 parts of potassium hydroxide in 50 parts of water. To the resulting ferric hydroxide precipitate is added 100 parts by volume of 15% sodium hypochlorite solution, giving a violet solution, which is heated briefly at 80 C. To this is added a solution of 13 parts of barium chloride in 50 parts of water. The purple precipitate which forms immediately is filtered and washed.

The barium ferrate, prepared as described, is added to a batch of 2-amino-3-chloro-anthrahydroquinone-disulfurio ester, prepared as described in Example 1. The oxidation is carried out at 60 C. There is then added 5 parts of potassium chloride. The mixture is filtered, concentrated to 50 parts by volume, salted at 60 C. with 7 parts of potassium chloride and 20 parts of methanol, and cooled thoroughly. On filtration, there is obtained a good yield of the yelloworange potassium salt of the leuco dichloro indanthrone tetrasulfuric ester.

Example 3 An aqueous solution of 12.5 parts of nickel chloride and 10 parts of sodium carbonate is oxidized by treatment with 100 parts by volume of 10% sodium hypochlorite solution. The resulting nickel dioxide is added to a batch of 2- amino-3-chloroanthrahydroquinone disulfuric ester prepared as described in Example 1. Oxidation is completed at 85 C. The reaction mixture is filtered, concentrated to 50 parts by volume, and salted with parts of potassium chloride followed by 12 parts of methanol. After thorough stirring, filtration gives a good yield of the light orange potassium salt of the leuco dichloro indanthrone tetrasulfuric ester.

Example 4 A mixture of 20.0 parts of the potassium salt of 2-acetylamino-3-bromo anthrahydroquinone- 9,10-disulfuric acid ester, 14 parts sodium hydroxide, and 120 parts of water is stirred at 85 Example 5 An aqueous solution containing the ferrate ion is prepared by adding a solution of 27 parts of ferric chloride in 100 parts of water to a solution of 40 parts of potassium hydroxide in 50 parts of water. To the resulting ferric hydroxide precipitate is added at 70, 100 parts by volume of 15% sodium hypochlorite solution. After stirring and heating at the mixture is filtered and a violet solution is obtained.

This violet solution, containing the ferrate ion, is added to a batch of 2-amino-3-chloro-anthrahydroquinone-disulfuric ester prepared as described in Example 1. After carrying out the oxidation at 60, the excess ferrate is removed by precipitation with barium chloride. The mixture is then filtered. concentrated to 60 parts by volume, salted at 60 with 12 parts of potassium chloride and 30 parts of methanol, and cooled thoroughly. On filtration, the potassium salt of the leuco dichloroindanthrone tetrasulfuric ester is obtained in good yield.

We claim:

1. Process of preparing leuco indanthrone tetrasulfuric esters which com rises reacting a leuco sulfuric ester of a beta-amino-anthra quinone having a free position alpha to the amino group with a compound containing as an anion iron having an even valence not less than 4 and not greater than 6.

2. Process according to claim 1 in which the iron compound is a ferrate.

3. Process according to claim 2 in which the beta-arninoanthraquinone is 2-arnino-3-halogenanthraquinone.

4. Process according to claim 3 in which the 2-amino-3-halogenanthraquinone is 2-ami11of5--chloroanthraquinone.

5. Process according to claim 4 in which the ferrate is an alkali metal ferrate.

6. Process according to claim 3 in which the ferrate is an alkaline earth metal ferrate.

'7. Process according to claim 6 in which the ferrate is barium ferrate.

8. Process of preparing a leuco indanthrone tetrasulfuric ester which comprises reacting the leuco sulfuric ester of a beta-aminoanthraquinone having a free position alpha to the amino group with compound of nickel having a valence of at least 3 and not more than 4.

9. Process according to claim 8 in which the nickel compound is nickel dioxide.

10. Process according to claim 9 in which the beta-aminoanthraquinone is 2-amino-3-halogenanthraquinone.

11. Process according to claim 10 in which the 2-amino-3-halogenanthraquinone is 2-amino-3- chloroanthraquinone.

12. Process according to claim 10 in which the 2-amino-3-halogenanthraquinone is 2-amino-3- bromoanthraquinone.

13. A process of preparing leuco indanthrone tetrasulfuric esters which comprises reacting a leuco sulfuric ester of a beta-aminoanthraquinone with a free position alpha to the amino group with a compound of cobalt having a valence of 3.

14. A process according to claim 13 in which the cobalt compound is cobaltic hydroxide.

15. A' process according to claim 14 in which the leuco sulfuric ester is of a 2-amino-3-halogenanthraquinone.

16. A process according to claim 15 in which the 2-amino3halogenanthraquinone is 2-amino-3-chloroanthraquinone.

WILLIAM B. HARDY. ROBERT E. FORTENBAUGH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,344,389 Bretagne et al Mar. 14, 1944 

1. PROCESS OF PREPARING LEUCO INDANTHRONE TETRASULFURIC ESTERS WHICH COMPRISES REACTING A LENCO SULFURIC ESTER OF A BETA-AMINO-ANTHRAQUINONE HAVING A FREE POSITION ALPHA TO THE AMINO GROUP WITH A COMPOUND CONTAINING AS AN ANION IRON HAVING AN EVEN VALENCE NOT LESS THAN 4 AND NOT GREATER THAN
 6. 